Centerless grinder



July 31, 1956 R. c. BARHORST CENTERLESS GRINDER 6 Sheets-Sheet 1 Filed July 1, 1953 INVENTOR. Romz' O, BARHQRST 31, 1956 R. c. BARHORST 2,756,546

CENTERLESS GRINDER Filed y 19 6 SheetsSheet 2 INVEN TOR. 03212? (QB/mam ATIDRMFY July 31, 1956 R. c. BARHORST CENTERLESS GRINDER 6 Sheets-Sheet 3 iled July 1, 1953 INVENTOR. Roam QBAR/Jom BY X ATYDRAEY July 31, 1956 R. c. BARHORST 2,756,546

CENTEIRLESS GRINDER Filed July 1, 1953 6 Sheets-Sheet 4 July 31, 1956 R. c. BARHORST 2,756,546

' CENTERLESS GRINDER Filed July 1, 1953 6 Sheets-Sheet 5 INVENTOR. ROBERT CBARHQRsT July 31, 1956 Filed July 1, 1953 R. C. BARHORST CENTERLESS GRINDER Sheets-Sheet 6 INVENTOR.

Ram QBARHQRsT United States Patent cnrsrnnrnss GRINDER Robert C. Barhorst, Pompton Plains, N. J., assignor, by mesne assignments, to Glebar Company, Franklin Lakes, N. J., a partnership Application July 1, 1953, Serial No. 365,367

14 Claims. (Cl. 51-403) The present invention relates to abrading or grinding machines, and, more particularly, to centerless grinders of the plunge-feed type, although certain features thereof are applicable to other types of center-less grinders.

The present invention is primarily concerned with centerless grinders for producing large numbers of small parts which are generally circular in cross-section. Such machines generally comprise a work wheel or grinding wheel, a regulating or feeding wheel, and a plunge-feed mechanism including a ram on which the latter wheel is mounted for moving the same towards and away from the work wheel. Since quantities of parts of various sizes and shapes and materials are to be produced on such machines, it is necessary to adjust the surface speed of the work and regulating wheels and the length of the stroke of the ram as well as the timing thereof.

Heretofore, grinding machines of this type have been proposed but have never been commercially successful because numerous interchangeable belts, cams, gears and levers or other mechanical means were depended upon to make these adjustments. Consequently, such machines required a great number of spare parts which increased the tooling cost of the machines and required interchanging of these parts each time it was desired to set up the machines for a different operation The present invention aims to overcome the foregoing difficulties and disadvantages by providing a machine of the character described herein which embodies many improved features, among which are separate drive means for the work and regulating wheels and a hydraulically operated system for controlling the ram, these being adjustable for producing various parts, including changing the relative speed of the wheels and the length of the stroke and the speed of movement of the ram; means for rendering the machine completely automatic in duplicating operations, including the feeding of work pieces in synchronism with the ram; spray means for cleaning the work wheel wherein the orifices are easily cleaned to prevent them from being clogged; shield means cooperating with the work wheel to confine a spray of cooling liquid within a predetermined zone and adapted to be dressed by the work wheel to cooperate therewith; improved mounting means for the work 'and'regulating wheels to maintain them in parallelism and to facilitate removal and replacement thereof; improved means for discharging the machined parts; and numerous other features which will become apparent from the detailed description herein.

Accordingly, an objection of the present invention is to provide such a machaine which has a low initial cost, a low operating cost, a low maintenance cost and a low tooling cost.

Another object is to provide such a machine which is simple and compact in construction and practical in use.

Another object is to provide such a machine which is readily adjusted, certain of these adjustments being adapted to be made while the machine is in operation.

Patented July 31, 1956 Another object is to provide such a machine which is vibrationless in operation and extremely accurate in duplicating the parts produced.

A further object is to provide such a machine adapted to produce parts formed of many different materials, for example, carbon, ceramics, cork, fiber, hard rubber, metal, plastics, wood and the like.

A still further object is to provide such a machine which is automatic, rapid and safe in operation, and requires a minimum of manual supervision.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:

Fig. l is a perspective view of a machine in accordance with the present invention.

Fig. 2 is a plan view of the top of the machine with certain parts broken away.

Fig. 3 is a fragmentary perspective view of a readily removable tail stock bearing for the Work wheel.

Fig. 4 is a fragmentary plan view of an improved spray pipe.

Fig. 5 is a enlarged fragmentary perspective view of the spray confining shield cooperating with the work wheel.

Fig. 6 is a fragmentary side elevational view of the upper portion of the machine.

Fig. 7 is a fragmentary sectional view taken substantially along the line 7-7 on Fig. 2.

, draulic system, and supporting a platform 11 at the top thereof; a work wheel 12 mounted on the stand; a work rest 14 cooperating with the work wheel; a ram 15 slidably mounted on the platform; a regulating wheel 16 mounted on the ram for cooperation with the work wheel; mechanism generally indicated by the reference numeral 17, for controlling the movement of the ram; and a magazine 18 for feeding pieces of stock to the wheels to produce parts therefrom.

These elements and the mechanisms associated therewith will now be described in detail.

The base The base or stand 10 of the machine is best illustrated in Figs. 1, 2, 7 and 8, and comprises a frame structure of a strength to support the various mechanisms thereon, and a casing or housing enclosing the front and sides thereof to confine the drive motors and the hydraulic system therein in the manner described hereinafter, whereby a neat, safe and compact arrangement is provided. The stand has a height of about that of a work bench or tool stand so that the platform 11 and the other elements supported thereon are at a level to facilitate manual supervision and interchanging of various elements.

The work wheel The work wheel 12 is shown completely or partially in Figs. 1, 2, 3, 5, 6 and 7', and is rotatably supported by a housing (Figs. 1, 2, 3, 6 and 7) mounted on top of the stand adjacent the back thereof. This housing comprises a casing part 21 for enclosing the top and back of the work wheel and having a side 22 provided with a bearing 24 (Fig. 2), and a second part, constituting a side frame or bracket 25 opposite the side 22, has a hearing 26 therein in alignment with the bearing 24.

The work wheel 12 is removably held on a shaft 27 for rotation therewith. One end of this shaft extends through the bearing 24 and carries a pulley 29 adapted to be driven in the manner as described hereinafter. This side of the housing may be termed the head stock. The other end of the shaft 27 is supported by the bearing 26 of the bracket 25 which may be termed the tail stock of the housing.

As shown in Figs. 2, 3 and 7, the tail stock part 25 is removably secured to the platform adjacent the open end of the casing part 21 which preferably has a recess or opening for receiving a portion of the tail stock part to put the parts 21 and 25 together in a manner to align the bearings 24 and 26 thereof. The part 25' is readily removed whereby access to the work wheel for removing and replacing the same is made possible.

The work wheel shaft or spindle 27, by being supported at both ends thereof, is accurately maintained in a predetermined position to facilitate alignment of the regulating wheel 16 in parallelism therewith, and spindle whip thereof is prevented to assure uniformity of the finished parts.

The work wheel spray pipe In order to lubricate the work wheel and clean the same, a spray pipe 30 (Figs. 2, 3, 4. and 7) extends through an opening, in the tail stock bracket 25' and carries a flange or collar 31 which is removably secured to the bracket (Figs. 3 and 4) by bolts or screws. The spray pipe has a closed inner end and has a plurality of orifices 32 for directing a spray of water upwardly against the back of the work wheel (Fig. 7). The pipe is coextensive with the work wheel and is parallel to the axis of rotation of this wheel.

This arrangement facilitates positioning the spray pipe orifices with respect to the work wheel in the foregoing manner, in the event the spray pipe is removed and replaced. However, the spray pipe can also be cleaned without removal of the same by providing the outer end of the spray pipe with an opening which is in alignment with the bore thereof, and applying a readily removable fitting or closure 34 to the open outer end of the pipe which has an inlet 35 for connecting a flexible water supply hose thereto. Upon removal of this closure, a brush can be inserted into the pipe to scrub the same and clear the orifices of any particles that may have obstructed the same.

The spray of water is confined within the work wheel housing, and is prevented from being thrown by centrifugal force from the wheel by a shield 36 (Figs. 5 and 7) extending across the front of the work wheel housing and being secured thereto. The lower edge of the shield is closely adjacent the work wheel and conforms to the contour of the wheel to serve in effect to seal in any water carried by the wheel. This arrangement is attained by formation of the shield of plastic material, preferably of the transparent type, and dressing of the lower edge thereof with the work wheel to conform the same with the wheel.

The shield 36 not only confines the sprayed water, but

also directs the water to the actual line of contact of the.

work wheel and the work piece.

The spray water, after being directed on the Work wheel, is deposited on a trough 37 (Fig. 7) below the wheel and is drained from the trough through an open,-

4 ing (not shown) at the back of the stand. If desired, the spray water may be collected in a tank, filtered and recirculated to reduce water costs.

The work rest The work rest 14 is removahly bolted at both ends to the work wheel housing (Figs. 2, 6 and 7), and is accurately positioned adjacently and in parallelism with the work wheel by a plurality of shimsv or thickness gauges 46 disposed between the front face of the housing and the work rest. This arrangement enables the work rest to be accurately located with respect to work wheels of various diameters to thereby facilitate interchangeable work wheels to be used on the machine.

Since the work rest is fastened at both ends, vibration thereof is prevented to assure a vibrationless support for the parts being ground and to prevent damage to the work rest by the work wheel.

T he regulating wheel mm The ram 15 carrying the regulating wheel 16 is best illustrated in Figs. 2, 6 and 7.

The ram is slidably mounted on a horizontal slide supported by the platform 11 for movement towards and away from the work wheel 12 in a direction perpendicular to the axis of rotation of the work wheel, and is arranged on the slide to prevent lateral movement or deviation from true perpendicularity. The slide is secured to the platform by a number of bolts 46 extending through slots 47 in the. slide to enable the slide to be adjusted inwardly and outwardly with respect to the work wheel. The slide has a stop 49 (Fig. 7) at its inner end for limiting the inward movement of the ram upon engagement by the inner end of a rod 50 threaded through a depending lug 51 of the ram. The outer end of the rod extends to the front of the machine and carries a manually engageable knob 52 having index. means 54 thereon for adjusting the rod 50 with respect to the stop 49 micrometrically, whereby the diameter of the parts ground between the work and regulating wheels can be controlled within accurate limits. The rod 56 is securely held in its position of adjustment by a set screw which is readily accessible from the top of the ram (Fig. 2).

The regulating wheel 16 is mounted on the inner end of the ram 15 by a yoke 59 which is pivoted on a stud 6t and is secured to the ram by a pair of screws 61 (Figs. 2 and 7).

The stud has an eccentric stern, as shown in broken lines in Fig. 2, which is mounted on the ram, and thus enables the yoke to be moved towards and away from the work wheel within a short range.

The yoke comprises. an arcuate shield section 62 for the upper outward portion of the regulating wheel, and parallel side portions 64 at the ends of the shield section, each having a bearing 65 (Fig. 2).. The regulating wheel is mounted on a shaft 66 having the lefthand end supported by one of the bearings and having the righthand end extending through the other hearing, as viewed in Fig. 2.

The ram 15 has a pair of lugs 67, one at each side, facing an outer straight edge 69 of the section of the yoke secured to the ram by the screws 61, and micrometer adjusting screws 70 are threaded through the lugs 67 and have their free ends engaging the straight edge 69. Upon loosening of the screws 61, the screws 70 can be set to adjust the yoke so that the axis of rotation of the regulating wheel is in true parallelism with the axis of rotation of the work wheel.

Since. both the work and regulating Wheels me. rotatably' supported at both ends thereof, they are maintained in such parallel relation at all times during the operation of the machine, particularly when pressure is applied on the work piece during the grinding thereof.

am ne- The ram operating mechanism The ram 15 is reciprocated inwardly and outwardly by duit means 77 and 78 at the ends of the cylinder for.

respectively supplying and alternately discharge hydraulic fluid to effect reciprocation of the piston, and a piston rod 79 carried by the piston and having a section thereof extending out of the cylinder for reciprocating the slide in the manner about to be described.

The free end 82 of the piston rod 79 extends into a bore 80 of the ram 15 and engages a relatively strong spring 81 within the closed end of the bore through which the ram is moved inwardly towards the work wheel by the piston rod (Fig. 7). v This spring serves two useful functions. It provides a resilient or yieldable connection between the piston rod and the ram which prevents damaging impact when the rod 50 engages the stop 49, and also permits relative movement between the piston rod and the ram after the rod has engaged the stop due to the compression of the spring 81. This relative movement is taken advantage of to allow the ram to dwell for an interval of time while the work and regulating wheels are finishing the parts being ground, before the ram is retracted or moved outwardly again.

This latter movement is effected by a collar 85 secured to the piston rod 79 which is normally urged by the spring 81 against a stop 86 secured to the ram at the upper outer end thereof, whereby upon movement of the piston rod towards the left (as viewed in Fig. 7) engagement of the stop 86 by the collar 85 causes the ram to' be retracted. While the ram dwells due to compression of the spring 81, the collar 85 moves away from the stop 86 (towards the right as viewed in Fig. 7) until it engages the rearward end surface 87 of the ram which acts as a stop to limit compression of the spring 81. I

It will be noted that the hydraulic cylinder and its piston rod are centralized with respect to the ram and the regulating wheel, whereby pressure is evenly distributed over the work and regulating wheel surfaces to produce identical parts from any section along the length of the work pieces. 7

The ram 15 carries cams which cooperate with switches for reversing the direction of movement of the ram and for controlling the magazine, the operation of which will be described hereinafter. These elements include a stationary microswitch 90 mounted at one side of 'the cylinder 75 and operated by a cam rod 91 secured to the ram and extending towards the front of the machine for controlling the flow of fluid to the cylinder 75 to cause the ram to be moved inwardly; a second microswitch 93 similarly mounted at the other side of the cylinder and operated by a second cam rod 94 similarly secured to the ram for causing a work piece to be fed from the magazine 18 at or about the time the ram is caused to be moved inwardly; and a third microswitch 95 carried by the ram and operated by a cam mechanism 96 for controlling the flow of fluid to the cylinder to cause the ram to be retracted.

The cam mechanism 96 controls the interval of time the ram is allowed to dwell with the regulating wheel in its work feeding position, and comprises a cam rod 97 having a central cam section for operating the switch 95, a pair of spaced apart lugs 98 on the ram slidably supporting the cam rod at the ends thereof, a light compression spring 99 cooperating with one of the lugs 98 and the cam rod 97 to urge the latter towards the left (as viewed in Fig. 7), a head 100 on the cam rod at the outer side of the other lug, and a screw 101 threaded through the piston rod collar 85 having its free end positioned for engaging the head 100 and provided with a lock nut 102 for securing the same in positions of adjustrnent.

The cam mechanism 96 is actuated during the time the spring 81 is being compressed and the collar moves forwardly with respect to the ram, so that, upon engagement of the head 100 by the screw 101, the cam rod 97 is moved forwardly to operate the micro switch associated therewith.

The adjustment of the screw 101 determines the exac moment the ram is caused to be retracted, whereupon the screw 101 disengages the head and the spring 99 returns the cam rod 97 to its initial position.

As previously indicated, the extent of inward movement of the ram is governed by the adjustable rod 50 which engages the stop 49. The extent of outward movement or the length of the stroke is governed by adjustment of the camsection of the cam rod 91 with respect to the microswitch 90 associated therewith. Similarly, the instant a work piece is to be fed from the magazine is governed by adjustment of the cam section of the cam rod 94 with respect to its microswitch 93.

Work piece feeding and parts removal The magazine 18 may be of conventional construction, and, as shown in Figs. 1 and 7, includes a work piece supply box 104, a hopper having a chute section 105 formed with an opening 106 adjacent the front of the shield 36 through which work pieces W are fed to the wheels 12 and 16, and a gate 107 (Fig. 7) under the control of a solenoid (to be described hereinafter) for causing the work pieces to be fed one by one in response to operation of the switch 93.

The work pieces are dropped on the work rest 14, and are held between the wheels 12 and 16 to produce the parts therefrom whichthen drop into the trough 37. In order to insure delivery of the parts to the trough and to break the fall thereof to prevent damage thereto, a flexible flap or apron 109 (Fig. 7), coextensive with the grinding wheels, has one end secured to the inner end of the ram 15 just below the regulating wheel 16 and has its other end extending into the trough. The flap, in this manner, prevents the parts from landing on the platform portion beneath the work rest, and the flap is agitated by the movement of the ram to shake the parts therefrom into the trough.

The flap or apron 109 preferably is formed of a sheet of rubber, rubberized fabric, flexible plastic or some other pliable water repellent material which will not mar the parts.

. T he wheel drive means In accordance with the invention, extreme flexibility in the setting up of the machine for producing various types of parts is provided'for by separate drive means for the work Wheel and the regulating wheel.

As shown in Figs. 2, 6 and 8, the work wheel shaft pulley 29 is driven directly by a motor 110 (Fig. 8), mounted within the stand 10, through a pulley 111 on the motor shaft and a belt 112 connecting the pulleys 29 and 111.

The regulating wheel shaft 66 is driven by a motor 114 (Fig. 8) through a gear box 115 having a sprocket 116 on its output shaft, a chain 117 connecting this sprocket to a'sprocket 118 on a stub shaft 119 (Figs. 2 and 6) carrying a gear 120, a gear 121 meshing with the gear and mounted on a second stub shaft 122 which is journalled for rotation adjacent the regulating wheel, and a flexible coupling 123 connecting this shaft to the regulating wheel shaft 66 to permit reciprocating movement of the regulating wheel during rotation thereof. The gears 120 and 121 are at the outer end of their respective stub shafts and are mounted thereon to interchange the same without disturbing the chain and sprockets.

Several sets of interchangeable gears like the gears 120 and 121 may be supplied with each machine to facilitate a wide and accurate range of speed adjustment of the regulating wheel with respect to the work wheel in a minimum time and in a simple and convenient manner.

The motors are concealed within the stand but are 7 readily accessible from the back thereof, while the drive pulleys, sprockets, belts and chains are encased in guards which are. readily removable and replaceable.

The hydraulic system The hydraulic system for supplying fluid to the cylinder is illustrated in Figs. 8' and 9, and generally comprises a motor a pump 126 driven by the motor, a hydraulic accumulator 127, a flow reversing valve 128, solenoids 129 and 130 for operating this valve, an adjustable one way return flow restricting valve 131, and a reservoir 132 for hydraulic fluid. All of these elements are mounted on a drawer or chassis 133 at. the. front of the stand which carries a panel 134 constituting a front end closure for the stand. In this manner, the hydraulic system is compactly arranged, and is concealed from view, but is readily accessible. Adjustment of the valve 131 can be made, without sliding out the drawer, by means of a knob 135 on a stem 136' extending through the front panel.

As described in greater detail with reference to Fig. 9, the flow reversing valve 128 is of the shuttle: type. and comprises a housing 137 having a centrally located inlet port 139, outlet ports and 141 and. return ports.142 and 143;. and a slidable valve member 144., adapted to. be moved back and forth in the housing by the solenoids 129 and 130, having recesses 145, 146 and 147 therein for the purpose about to be explained.

The inlet port 139 is connected to the outlet of the pump 126 by a conduit in which the accumulator 127 is connected, and the inlet of the pump is connected to the reservoir 132 by the. conduit 151. The outlet port 140 is connected to the cylinder 75 by the conduit 77 to supply fluid for moving the piston in the. direction to cause the ram to be moved inwardly during the feeding stroke, and the outlet port 141 is connected to the cylinder by the conduit 78 to supply fluid for moving the piston in the opposite direction to cause the ram to be moved outwardly or retracted during the return stroke, the. valve 131 being connected in the conduit 78 for the purpose about to be made apparent. The return ports 142 and 143 are connected to the reservoir by a conduit 152.

When the valve member 144 is. at the left of its, housing, as. shown in Fig. 9, fluid flow communication is established between the inlet port 139 and the outlet port 140 by the recess 145 to direct fluid to the cylinder by way of the conduit 77, and fluid flow communication is established between the outlet port 141 and the return port 142 by the recess 146 to permit fluid to leave the cylinder by way of the conduit 78. Alternately, when the valve member is at the right of its housing, fluid flow communication is established between the inlet port 139 and the outlet port 141 by the recess 145, and fluid flow communication is established between the outlet port 140 and the return port 143 by the recess 147'. The solenoid 129- is adapted to move the valve'mem-ber to the left, while the solenoid 130 is adapted to move the valve member to the right upon momentary energization thereof.

The one way flow restricting valve 131, connected in the conduit 78, is constructed and arranged to restrict the return flow of fluid from the cyclinder 75 but to permit free flow of the fluid to the cylinder, whereby this valve serves to slow down the feed stroke of the cylinder but enables the return stroke to take place rapidly.

To accomplish the foregoing, the valve 131 comprises a housing having ports 156 and 157, respectively, indirect communication with the cylinder 75 and the port 141, a valve seat 158 between the ports 156 and 157 having an opening 159 about equal to the bore of the conduit '78, a checkvalve member 169 slidably arranged in the housing between the port 156.- and the seat 158 and provided with an opening 161 smaller than the opening 159, and a tapered portion 162 on the adjusting. stem 136. extending partially into the opening 161 tov restrict. the same when the valve member 160 is seated. but being inefiective to restrict flowwhen the. valve member 160 is I the speed of the feed stroke can be accurately adjusted in a practicai and convenient manner without resorting to a set of interchangeable cams or other complex mechanisms.

The operation of the machine Assuming that the switch 90 has been manually operated to actuate the'solenoid 129 to position the shuttle valve member 144 as shown in Fig. 9, the piston 76 is now in its feed stroke. Fluid flows from the pump 126, through the valve 128 and the conduit 77. to the cylinder 75 in back of. the piston 76. causing the piston to move towards the right as viewed. Fluid in the cylinder at the right or in front of the piston flows through the conduit 78 and the valves 131 and 128. to reservoir 132. The flow of this fluid in passing through. the valve 131 is restricted by the opening161 of the check valve member 160 which is moved on its seat 158 by the fluid, the amount of such restriction being adjusted by the portion 162 on the stem 136, so that the. movement of the piston '76 is retarded and therfigulating. wheel ram moves slowly during the feed stroke thereof.

' its. housing to condition the valve 128 for controlling the return stroke. Fluid flows from the pump 126, through the valves 128 and 131 and the conduit 78 to the cylinder 75 at the right of the piston, as viewed, causing the piston to move. towards the left. This fluid in passing through i the. valve 131 unseats the check valve member and passes directly through the opening 159 of the seat 158 without any flow restricting effect. At the same time, fluid in the cylinder at the left of they piston freely flows through the conduit. '77 and the valve 128 to the reservoir 132, whereby the movement of the piston is unretarded and the ram is moved. rapidly during its return stroke.

When the ram. has been retracted the desired distance, the cam rod means 91 and 94 momentariiy close their respective switches 90 and 93, whereby the solenoid 129 is. again actuated. to condition the valve 128v for controlling the feed stroke and a solenoid 16.4 is actuated to operate the gate 107 for releasing a work piece from the hopper throat 105 just as. the regulating Wheel approaches the work wheel.

The machine now is in automatic operation and the cycle, including the. feed stroke, work piece release and the return stroke, is repeated until the machine is. shut off manually.

While the electrical energy for the solenoids is shown schematically as being supplied from several sources, it will be understood that, in practice, they are operated from a single source.

From the foregoing description, it will be seen that the present invention provides a centerless grinding machine having many novel features and advantages which enable the machine to be operated at many different speeds of wheel rotation or ram movement with ram strokes of varying lengths. This is accomplishd without resorting to complicated cam sets or other mechanism which requires considerable. time to set up. for a particular operation. The machine in accordance with the invention on the other hand can be quickly and accurately adjusted for performing a wide variety of operations in a highly simple and convenient manner. Furthermore, the machine can withstand continuous use over long periods without parts getting; out of alignment or being, worn or otherwise impaired, whereby servicing and maintenance costs are greatly reduced.

As various changes may be made without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

Iclaim:

1. In a grinding machine of the class described, the combination of a work wheel, a slidably mounted ram, a regulating wheel on said ram, fluid pressure medium operated means including a cylinder, a piston and a piston rod for moving said ram towards and away from said work wheel to feed and return said regulating wheel, a spring positioned between said ram and said piston rod, a stop for limiting the movement of said ram towards said work wheel, means for supplying fluid pressure medium including a pump and a reservoir, a valve and conduits for establishing connections to supply pressure medium to one side of said piston to move the same in a direction to feed said regulating wheel and to return pressure medium from the other side of said piston to said reservoir and alternately to supply pressure medium to said other side of said piston to move the same in a direction to return said regulating wheel and to return pressure medium from said first mentioned side of said piston to said reservoir, means for operating said valve to alternately establish said connections, means for actuating said valve operating means operable to reverse said valve at about the completion of the feed stroke of said ram including a slideable cam and yieldable means for resisting movement of said cam, and means on said piston rod for effecting movement of said cam and render said valve actuating means effective upon compression of said spring after said ram engages said stop, and means for actuating said valve operating means operable to re-v verse said valve upon completion of the return stroke of said ram.

2. A grinding machine according to claim 1, wherein a stop engaging element is carried by said ram and means are provided to predetermine the position of said stop and said element to regulate the length of the stroke of said ram.

3. A grinding machine according to claim 1, including work piece supplying means, means for operating said last mentioned means to deliver one work piece at a time to said wheels, and means for actuating said supplying means operating means at about the completion of the return stroke of said ram.

4. A grinding machine according to claim 1, wherein the conduit for returning pressure medium from said other side of said piston to said reservoir includes flow restricting means whereby the feed stroke of said ram is slowed down.

5. A grinding machine according to claim 1, wherein the conduit connecting said other side of said piston and said valve includes a check valve means formed with a flow restricting opening and arranged to seat during the feed stroke of said ram whereby the feed stroke of said ram is slowed down and arranged to unseat during the return stroke of said ram whereby the return stroke of said ram is unimpeded.

6. A grinding machine according to claim 5, wherein said check valve means includes means for adjusting said.

flow restricting opening.

7. In a grinding machine of the class described, the combination of a frame, a work wheel supported by said frame, a ram slidably mounted on said frame, a regulating Wheel on said ram, a cylinder secured to said frame, a piston in said cylinder, a piston rod connected to said piston for moving said ram towards and away from said work wheel to feed and return said regulating wheel, a spring positioned between said ram and said piston rod, a stop for limiting the movement of said ram towards said work wheel, means for supplying hydraulic fluid under pressure including a pump and a reservoir, a shuttle valve and conduits for establishing connections to supply fluid to one side of said piston to move said ram towards said work wheel and to return fluid from 1O the other side of said piston to said reservoir and alternately supply fluid tosaid other side of said piston to move said rarn away from said work wheel and to return fluid from said first mentioned side of said piston to said reservoir, a solenoid for positioning said valve to effect movementof said ram towards said work wheel, a second solenoid for positioning said vvalve to effect movement of said ram away from said work wheel, a switch mounted on said frame for effecting energization of said first solenoid, an extension on said ram for momentarily closing said switch upon the completion of the return stroke of said ram, a second switch mounted on said frame for effecting energization of said second solenoid, and means on said ram for momentarily closing said second switch at about the completion of the feed stroke of said ram including a slideable cam and yieldable means for resisting movement of said cam, and means on said piston rod for effecting movement of said cam to operate said second switch upon compression of said spring after said ram engages said stop.

8. A grinding machine according to claim 7, including means for mounting said extension on said ram to predetermine its position with respect to said second switch.

9. A grinding machine according to claim 7, including work piece supplying means, a solenoid for operating said last mentioned means to deliver one work piece at a time to said wheels, a third switch on said frame adjacent said first switch for effecting energization of said last mentioned solenoid, and a second extension on said ram for momentarily closing said third switch at about the completion of the return stroke of said ram.

10. A grinding machine according to claim 9, including means for mounting said second extension on said ram to predetermine its position with respect to said third switch.

11. In a grinding machine of the class described, the combination of a table, a work wheel mounted on said table, a ram slidably mounted on said table, a regulating wheel mounted on said ram, means for effecting rotation of said wheels, a drawer slidably mounted in said table, hydraulic fluid operated means for actuating said ram, and means for supplying hydraulic fluid under pressure to said last mentioned means mounted on said drawer including a hydraulic fluid reservoir, a pump, a motor for operating said pump and valve means for controlling said ram actuating means.

12. In a grinding machine of the class described, the combination of a support having a trough provided with an opening, for receiving the parts worked upon by the machine, a work wheel on said support above said trough and spaced therefrom, a ram slidably mounted on said support, a regulating wheel on said ram positioned to cooperate with said work wheel, and a flexible flap having one edge attached to said ram and extending under said regulating wheel and into said trough beneath said Work wheel to receive the parts and direct the same into said trough.

13. In a grinding machine, a housing providing an enclosure having an open front, a Work wheel supported by said housing within the enclosure adjacent the front thereof, a regulating wheel positioned to cooperate with said Work wheel to define a grinding throat, a work rest beneath the grinding throat with its upper edge adjacent said work wheel, and a sheet of plastic depending from said housing at the front thereof and having its lower edge above the grinding throat and being in engagement with said work wheel.

14. A grinding machine according to claim 13, including a spray pipe in the enclosure for directing liquid on said work wheel, said work rest and said sheet being constructed and arranged to cooperate to confine the liquid within the enclosure.

(References on following page) 11 References. Cited in. the filfl of this patent, $985437 .02 3 UNITED STATES PATENT S 7 2,065,099 618,293 Ridl'ey Ian. 24,1899 2,065,100 987,982 Hardie Mar. 28, 1911 5. 2,147,891 1,416,462 Hanson May 16', 1922' 2,163,967 1,416,463 Hanson May 16, 19.22 2,224,423 1,483,748 Sanford Feb. 12, 1924 2,228,386 1,680,360 Bath Aug, 14,. 1928' 2,363,831 1,721,477 Spaflord July 16, 1929 10 2,382,311 1,777,607 Ekholm Oct. 7, 1930 2,478,562 1,840,231 Harrison Ian. 5, 1932 2,496,520 1,844,653 Hechenbleikner Feb. 9, 1932 2,567,589 1,969,997 Wood Aug. 14, 1934 2,597,242 1,982,298 Haas Nov. 27, 19.34 15 2,633,674

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